EAGER: Unravel, mimic and control physiology via chiral-induced spin selectivity: a quantum approach

本项目旨在揭示和控制纳米尺度上的“手性诱导自旋选择性”（CISS）效应。CISS是一种不寻常的行为，最初是在生物结构中观察到的，后来才被用于技术应用。它描述了这样一个事实：在室温下，电子通过具有手性（或镜像）对称的分子（例如DNA）传递，有利于一种称为自旋的量子特性的特定状态。这种自旋偏好有效地转化为通过手性分子比通过非手性分子更有效的电子传递，这一性质理所当然地引起了人们的极大兴趣。对映体（互为镜像的手性分子）具有相反的电子自旋取向偏好，这可以为药物开发提供信息；任何依赖于最佳电荷传输的技术——也就是整个电子工业——都可以从利用和控制ciss效应中获利。由于蛋白质和大多数生物分子都是手性的，CISS也可能对信号传导有巨大的生物学意义。这项研究属于新兴的“量子生物学”领域，该领域研究量子力学定律如何在生物功能中发挥作用。这项工作将促成美国第一个虚拟量子生物学中心的建立。这样一个中心将成为量子生物学从业者互动、合作和向更广泛的公众传播他们的发现的自然组织结构。该中心的成员将揭开生物学中量子效应的神秘面纱，并批评其潜在的可疑主张，并将这一领域置于公众眼中坚实的科学基础之上。该中心还将推动诸如量子生物学每周在线会议等活动，该会议已经由PI组织了一年多。手性诱导自旋选择性（CISS）描述了这样一个事实，即在室温下，电荷通过手性分子的传输有利于特定的电子自旋方向（或“自旋极化”）。由于CISS效应，对映体具有相反的电子自旋取向偏好。这一发现可能具有巨大的生物学意义，因为蛋白质和大多数生物分子都是手性的。在纳米尺度上对CISS的明确理解仍然缺乏。在这里，研究人员建议在纳米尺度上阐明DNA中CISS背后的机制。目前，利用化学技术（如电化学、I-V曲线）研究CISS依赖于手性纳米结构与“经典态”电子自旋相互作用的系综；这分别排除了通过手性结构的总电荷的定量测量，以及“非平凡量子态”（例如，自旋叠加）中自旋在通过这种手性分子时的演变。所提出的设置——ESR-STM与单个手性分子一起工作，在“非平凡量子态”中注入电子自旋——将克服目前的实验限制，从而能够使用量子力学的语言和工具对CISS进行可预测的定量理解。研究人员将不同条件下的DNA（例如，稍微不同的温度，不同的DNA长度）连接到ESR-STM的尖端，并使用磁共振技术制备任意自旋状态的电子，然后将其注入分子中。通过表征电子相干如何通过不同的纳米手性电位传输，利用量子自由度劫持和驱动生理和生物信号处理成为可能，并模仿数百万年来自然发展和优化的策略来转导量子信息。该项目由生物科学理事会分子和细胞生物科学部分子生物物理集群支持。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

This project aims to unveil and control the “chiral-induced spin selectivity” (CISS) effect at the nanoscale. CISS is an unusual behavior first observed in biological structures, and only later harnessed for technological applications. It describes the fact that, at room temperature, electron transport through molecules with chiral (or mirror) symmetry -- e.g., DNA -- favors particular states of a quantum property called spin. Such a spin preference effectively translates into more efficient electron transport through chiral molecules than through achiral ones, and this property has justifiably attracted significant interest. Enantiomers (chiral molecules that are mirror images of one another) have opposite electron spin orientation preferences, which could inform drug development; and any technology that relies on optimal charge transport – i.e., the entire electronics industry – could profit from harnessing and controlling CISS-like effects. CISS might also have tremendous biological implications for signaling, as proteins and most biomolecules are chiral. This research falls within the emergent field of “quantum biology” that studies how the laws of quantum mechanics might play a role in biological function. This work will foment the creation of the first US-based virtual Quantum Biology Center. Such a center will become a natural organizing structure for quantum biology practitioners to interact, collaborate and disseminate their findings to the broader public. The Center members will demystify and critique potentially dubious claims of quantum effects in biology and place this field on firm scientific ground in the public eye. The Center will also catalyze events such as weekly online meetings on quantum biology, already being organized by the PI for over a year.The chiral-induced spin selectivity (CISS) describes the fact that, at room temperature, charge transport through chiral molecules favors a particular electronic spin orientation (or ‘spin polarization’). Because of the CISS effect, enantiomers have opposite electron spin orientation preferences. This observation might have tremendous biological implications, as proteins and most biomolecules are chiral. An unambiguous understanding of CISS at the nanoscale is still lacking. Here the investigators propose to elucidate the mechanisms behind CISS in DNA at the nanoscale. Currently, CISS is studied using chemistry techniques (ex.: electrochemistry, I-V curves) relying on ensembles of chiral nanostructures interacting with electron spins in “classical states”; this precludes, respectively, quantitative measurements of total charge going through the chiral structures and of how spins in “non-trivial quantum states” (e.g., spin superpositions) evolve when transported through such chiral molecules. The proposed setup – a ESR-STM working with a single chiral molecule that gets injected with electron spins in “non-trivial quantum states” – will overcome the present experimental limitations and thus enable a predictable, quantitative understanding of CISS using the language and tools of quantum mechanics. The investigators will attach DNA under different conditions (e.g., slightly different temperatures, a variety of DNA lengths) to the tip of the ESR-STM and use magnetic resonance techniques to prepare electrons in arbitrary spin states, which will then be injected into the molecule. By characterizing how the electron coherences are transported through the different nano-chiral potentials, it becomes possible to harness quantum degrees of freedom to hijack and drive both physiology and biological signal processing, and to mimic strategies developed and optimized by nature over millions of years to transduce quantum information. This project is supported by the Molecular Biophysics Cluster of the Division of Molecular and Cellular Biosciences in Biological Sciences Directorate.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.